1. Field of the Invention
The present invention relates generally to a remote controller for remotely operating electronic equipment and, more specifically, to a remote controller that can learn commands for operating such equipment.
2. Description of the Prior Art
Remote controllers that use infrared and electromagnetic waves to transmit modulated control data to remotely control electronic equipment such as, for example, television sets, stereo sets, and Video Tape Recorders (VTRs) are well known. For example, shown in FIG. 1 is an infrared remote controller that has a light transmitter 1 consisting of an infrared ray transmitting element and an infrared transmission filter at its front end, and a number of operating keys or buttons 2 on its upper surface. Each of the operating keys 2 can cause an electronic appliance or equipment to perform some operation. For example, in a television receiver a button PW could turn the electric supply on and off, and keys numbered "1" to "12" could represent television channels.
Reference character 2M shown in FIG. 1 designates a mode key for selecting a set-up operation of the control signal which has been preset in a manner to be described below. By switching the mode key 2M from the operational mode, in which the control signal is output in correspondence with the operation of one of the buttons 2, to the select set-up mode the desired control signal is selected from the control signals as preset data for performing the select set-up operation corresponding to the operating key 2.
A command signal is typically obtained by modulating a fixed frequency carrier and is then transmitted as an infrared ray. Many different command formats are available depending on the carrier frequency, the pulse bit periods, and frame structures. Thus, the coding systems are different depending on the format adopted. There are many cases where these formats vary with the maker, model, or year in which the electronic equipment was manufactured. Because the remote controller has to be exclusively prepared in accordance with each various electronic appliance, the user has to set up the remote controller so that it can be used with the particular desired electronic appliance.
In response to this situation, remote controllers have been developed that store in advance, or are preset, and can output groups of control signals having different signal structures, such as formats and code systems, for various manufacturers and different models of electronic equipment. These controllers are referred to hereinafter as preset remote controllers.
Also well-known are so-called "learn" type remote controllers, in which control signals are not preset and the control signals are stored by the user using another remote controller intended specifically for the electronic equipment being controlled. In the case of the learn type remote controllers, however, the user has to cause the remote controllers to learn the control signals one-by-one corresponding to each operating key and, hence, the set-up operation prior to use is lengthy and complicated disadvantageously. In general, preset type remote controllers or other remote controllers to which the learn function has been added are widely used.
With the preset remote controllers, as shown in a table of FIG. 2, the control signal groups for the electronic equipment corresponding to each of the various manufacturers, for example, "A" corporation through "I" corporation, are preset in, for example, a read only memory or ROM. When a manufacturer such as "B" corporation has two kinds of control signal groups having different formats and/or code systems, for example, code CB1 and code CB2, these are then preset separately.
Each control signal group is then allotted to a numbered key and the user can call up the desired control signal group by the select set-up operation. For example, if key number "1" and the PW key are pressed together, the control signal group with the format and code system adopted by "A" corporation will be selected, and when the several other operation keys 2 of the remote controller are pressed the control signals for "A" corporation's equipment will be produced.
With the preset remote controller described above, each type of control signal group is preset into the unit. This means that when setting up equipment modes using a select set-up operation that employs the numbered keys, the number of control signal groups that can be preset is limited to the number of operating keys 2, that is, the quantity of numbered keys present. Also, if there are a very large number of different kinds of control signal groups and if just twelve presets are assigned to certain control signal groups, then there will still be groups that cannot be preset, and the remote controller will therefore not be able to operate the electronic equipment corresponding to these leftover groups.
On the other hand, when presetting using numbered keys for a large number of types of control signal groups, it is possible to store the control signal groups by using two or more numbered keys corresponding to each control signal group, as shown in FIG. 3.
In this case, if the user holds down the PW key and then presses key "1" and key "2", the control signal group CA2 having the code system and format for "A" corporation will be selected. By doing this it will be possible to store almost any number of types of control signal formats and codes, although this will of course depend upon the amount of memory space available in the ROM.
Nevertheless, this does present a problem in that the select setting operation becomes very complicated. Also, the user may know the name of the manufacturer of the electronic equipment being used but it is unlikely that the user will have an understanding that goes as far as knowing the control signal format or the control system. Thus, the user will not know which of the three codes CB1 to CB3 should be selected, and so will have to repeat the complicated select setting procedure until the correct control signal for operating that product has been output. Therefore, if a variety of kinds of control signal groups are preset, the operating property of the remote controller will be deteriorated.
Furthermore, there is a case where the user might not know the name of the manufacturer of the electronic equipment being used by him or her. In this case, it is almost impossible to perform the select set-up operation and it is impossible to use the preset remote controller.
There are also other remote controllers that are popular, particularly in European countries, in which the control signals are in the form of "toggle" codes. In such toggle codes a toggle bit is provided in a portion of the control signal and the toggle bit is outputted in a reversed manner for every alternate operation. For example, the toggle bit outputted by the first operation is "0", the toggle bit outputted by the next operation is "1", and the toggle bit outputted by the next subsequent operation is "0" again, and so on. Thus, the toggle bit of the control signal is changed back and forth between the odd and even numbers of operation times.
There are some advantages in this system. For example, the user may press key "1" twice, but the electric equipment does not discriminate between selection of channel "11" from the selection of channel "1" twice. The electric equipment measures an interval between the first key operation and the second key operation and the interval is compared with a predetermined time. If the interval time is less than the predetermined time, the central processing unit discriminates selection of channel "11". on the other hand, if interval time is greater than the predetermined time, the electric equipment discriminates selection of channel "1" and the judgement is quickly reached by using the toggle codes.
If the user pressed the key "1" continuously, and if an obstacle crossed between the electric equipment and the remote controller, then the remote control signal is interrupted. Nevertheless, the electric equipment does not discriminate between the operation of the same key twice or the interruption of the remote signal. Because the control signal includes information relating to the number of operation times, then the equipment is able to discriminate between the operation of the same key twice or the interruption of the remote signal.
Such system suffers from a problem in that it is impossible to effect the so-called "learn" mode with the control signal in the form of the toggle codes. Namely, in the case where the control signal in the form of a certain toggle code is learned, what is learned and stored is only the code inputted through the learning operation when the toggle bit is either "0" or "1". For example, assuming that the toggle bit of the control signal during the learn input is "1", when the learned control signal is outputted, the toggle bit is always kept at "1". Accordingly, it is impossible to receive a correct control signal in the electronic equipment of the kind that responds to the toggle code system.